Sadly with most sound equipment you have to buy before you try. I bought a pair of really expensive so called pro headphones recently they were crap. They sounded terrible and there was massive leakage. I had no way of testing them first and there was a label on them stating that "due to risk of infection we cannot accept returns on headphones or microphones unless they are defective" In other words you pays your money you takes your chance.
It is always best to thoroughly research purchases....try them first if you can. So many manufacturers make claims that cannot be substantiated or are gross exaggerations. Best to get a friend to recommend first. There are sites where stuff is reviewed but even the reviews are conflicting and sometimes biased.

http://www.soundclick.com/bands/songInfo.cfm?bandID=687727&songID=5238055